Title is self-explanatory.
I also wanna hear out your opinions on this; be honest with it and try to control your anger if you comment in a rant as an answer to this.
As a Yasuo main myself, I'm relatively nice and easy-going to other people but there are those times where in I'm just straight-up pissed where I'm not gonna be toxic and instead be sadistic and condescending as hell and just say, "kill that bastard" in the chat when I wanna kill someone.
he feels unfair to play against
and also a lot of yasuo players feed their asses off.
To be fair it is a generalization fed by confirmation bias. People hate the champion, and that just bled over to the players of that champion.
The champion has an overloaded kit, he can do a lot of things that others cannot, and there is this perception that the champion is powerful. Thus people expect the champion to perform well. Teammates of Yasuo players expect them to play well and be OP, meanwhile any new Yasuo players expect to do well because they think he's OP too.
What people don't think about is that his kit also has a higher skill floor than they expect. On top of that, his kit is probably very fun to execute (wouldn't know, I think I only ever played him once), and feels very skillful to do well with. so Yasuo players who do well often get a big head about it and taunt / spam mastery.
When things go south, everyone's expectations go down the toilet and they become upset that things are not going as they planned. Oftentimes when expectations are violated, toxicity ensues. The new Yasuo player is upset they are not actually OP, and the team hates them for doing badly when they were expected to do well. Everyone thinks, 'wtf this isn't how its supposed to work,' and begin looking for reasons to blame.
This also applies to the enemy team, if they see a Yasuo on the opposing team they expect him to be OP and prepare themselves for a frustrating game. So if things go well for the Yasuo they just think, meh it's to be expected, he's OP. Stupid champ is overloaded and should be nerfed. And if it goes poorly for the Yasuo, they feel vindicated taking out their frustration with the kit by stomping him and tilting him and his team in all chat.
It's a self-feeding hatred that the community has built up over time. People always notice when something negative happens, and rarely notice when it goes well instead. Over many many games of only noticing the negative experiences surrounding the champion and his playerbase, everyone has built up a huge confirmation bias against him.
The resulting expectation is that, 'if the enemy team has Yasuo he's going to be OP, and if we have him he's going to be a toxic scrublord and a feeder.'
Because every one that plays that champ is an arrogant asshole that is either shit at playing him or godlike and it's more binary than a fucking computer code plus Yasuo is toxic as hell and should be deleted from the game and removed from all league of legends players memories in a similar fashion to Men In Black
Because most Yasuo mains think they are god and will always blame their teams for their mistakes, and sometimes they will accuse the enemy(s) of using scripts when they misplay or they get outplayed.
People hate playing against Yasuo. He is so unfun to play against that one of my friends who started playing couple of months ago deleted the game because he was sick of playing vs Yasuo and Lee in normals every single game. I know its so fun to play Yasuo, but you HAVE to understand that you are literally ruining the game for at least your lane opponent, especially if its an unexperienced player. That is why everybody hates Yasuo and thus hates you as a person who plays him every game or to put it like this - ruins every single game they play. Its the same with Riven, Lee or Vayne.
because he can suck in lane, i destroy him, his vi or some other bs with a knock up will gank, he gets a free ult, then spams mastery like he outplayed me.
not once, twice, or even three times.
almost every time im against that stupid fking champion.
Because anything yasuo related that isn't an insult to the character or his playerbase gets downvoted to oblivion.
Gaming communities can get a lot on the Pitchforks&Torches side when they hate something.
If you are vs him, he's very annoying to fight against, and whenever they kill you they tend to disrespect ( writing ez in chat, mastery spam, etc). Even if you manage to kill them or simply not to die, they probably will get fed from your teammates since people tend to ignore SS pings (low elo :c )
If they are in your team, they either feed, blame the team and go afk, or actually perform well and get kills. From that moment, they will ignore objectives and permapush their lane without warding, challenging the other team to 1v1 and normally getting ganked by 2-3 people, giving lots of gold and throwing their advantage, just because they have to show they are REALLY GOOD at playing the game while actually having no idea apart from farming and 1v1 mechanics.
All together, whenever I see someone in my team picking Yasuo, i get scared because i can be 99% sure that he will behave like that, and he will turn the game in a 4 vs 6.
Please: Stop playing Yasuo and go try something healthier. For your own good.
Well when i used to top lane i would destroy him in laning phase, but then he gets 
and
and then win the game.
You'll never get an accurate answer. People will always say "he feeds his ass off" and you'll have others going "he's op" and you'll have others going "because yasuo mains are toxic"
You want my opinion? His windwall prevents him from being kited and a lot of ADCs are jealous of his 100% crit chance. Put yasuo against any skirmisher and he'll die. 
shits on him. 
shits on him. 
shits on him. The only time that yasuo can really beat those 3 in a duel, especially and because will just press r and make you have to run away(assuming you're playing yasuo) is if he lands his knock up followed by a and some auto attacks.
A level 7 yasuo main.
A lot of players are jealous that yasuo takes skill. So they try him and feed.
yasuo is the poster child of toxicity (but not all of them are, yasuo is just the worst offender)
its called memory bias.
People do this with more mains than just Yasuo. You could have played with hundreds of Yasuo mains who say nothing in chat, or are nice if they say anything, BUT because you also play with Yasuo players who are asshats and talk crap all game, those are the only ones who left any kind of impression on you and so you begin to associate all Yasuo mains with your remembered experience.
Basic psychology really. And its sad.
Free shield,ressource less , only need to pay 2 crits item to get 100% crit chance when other carries have to invest in 4 items for the same result. Low cool down tornado for hard shoving you under your tower all game . Wall immunity from projectiles. Close to no cool down gap closer, way to much wave clear, low cool down ultimate who place you out of tower range if you tower dive and free penetration on crit and since he hit 100% crit in 2 items it’s 100% pen to deny tank who try to itemize against him and conqueror just make it more frustrating. There.
For me its because I play supp. As a main of Thresh, Yas's kit counters me so hard if he plays right. He can make me useless easily, as well as many other champions. Its the same reason teemo was hated. His blind makes many champs unplayable into him back in his glory days. His shrooms made jungling hell, and any roams ended with multiple kills to him. A good yas can do the same and it tilts people off of the world.
Might as well make a League TV show called, "Everybody Hates Yasuo" and all it features is Yasuo doing crazy stuff and every single champion hates or berates him, but Yasuo manages to fight back.
Because the champion is given so many handicaps that when you fail on him it's pathetic, but when you succeed on him it's unsurprising.
To be clear, i don't hate yasuo mains, I hate the champion. Though i generally hate champions on the basis that they're handed too many answers, and I dislike people who enjoy being given handouts.
Going beyond skill floors and playstyle expectations, there's also a cultural element at play.
Yasuo, to describe him as bluntly as possible, embodies the stereotypical fangirl hero. Shirtless and brooding, Yasuo's lines are very melancholy, some would say 'emo', and to some ears, positively whiny. That sort of 'never my fault anti-hero' like Illidan Stormrage (Bonus points for sharing a VA) garners a certain expectation from some players.
That happens whether they know it or not as a subconscious side-effect of the champion. It's the same reason people generally assume that Tauren female players in WoW are middle-aged and upwards women, for example.
cause they are Yasuo mains
i dont know but almost they dont like him coz he can beat them
Il be honest, i personally love jasuo,riven, and vayne lore and the champs are well made, satisfactory to play and have a good skill cap but guess what i dont like.....disrespect.
When someone outplays me i recognize it and may even praise the person with a "wp" or "nice one" get back up and play it a lot safer but mastery spam and the "ez" are just stupid and leave me with a sour taste in my mouth rather than leaving any respect or sportsmanship towards that player, and yay riot added emotes not meant to be "toxic" and yea they arent toxic they are fucking NUCLEAR.
And i hate to break it to you but these champions have the most toxic and disgustingly rude and disrespectful players on the rift and frankly its sad that such champs have such a shitty player base. In all my time ive meet a friendly vayne, thats literally it just one.
Yasuo and Riven are yet to e found, and yea theres lots of toxic people out there who main other cancer champs but id say this 3 make about 70% of them alone 
The mastery 7 tilts them<3
THIS is why we hate yasuo mains
Yasuo main: dont ban yas Yasuo main: ffs Yasuo main: why
Guy who banned yasuo: Sorry mate my bad!!!
Yasuo main: why be an a55hole
Guy who banned yasuo:: sry
Me: Well enemy team banned it anyways! Me: No reason to get mad right? :D
Yasuo main: yes reason Yasuo main: Fu dude
Innocent Bystander: first team fight
Me: No no, no reason my friend :D
Yasuo main: i had it selected Yasuo main: and fu too
Innocent Bystander: just joking
Yasuo main: w/e plz die loser.
